Treatment beyond progression with nivolumab in patients with recurrent or metastatic (R/M) squamous cell carcinoma of the head and neck (SCCHN) in the phase 3 checkmate 141 study: A biomarker analysis and updated clinical outcomesRobert I. Haddad, Robert L. Ferris, Makoto Tahara et al.|Annals of Oncology|2017Cited by 36